Abstract: CO2 fluxes of Phyllostachys edulis ecosystem in Anji was 24 hours observationed using an eddy covariance method. Meanwhile， the chlorophyll fluorescence parameters of Phyllostachys edulis under the framework of CO2 fluxes were measured by PAM2500 chlorophyll fluorometer. The diurnal variations and monthly variation of net ecosystem carbon exchange （NEE） and the variations of chlorophyll fluorescence parameters were analyzed. The results showed that the monthly NEE was always negative in 6∶00—7∶00， positive in 17∶00—18∶00， indicating that Phyllostachys edulis assimilated CO2 in daytime. The highest NEE in the numerical value was autumn （September， October， November） > spring （March， April， May） > winter （December， January， February）， which showed that the NEE had obvious seasonal characteristics. The monthly variation range of NEE value was-25.563 3-85.531 2 gC·m-2·month-1， with the minimum in January. The maximal photochemical efficiency of photosystem Ⅱ （Fv/Fm） showed the trend of down after rise， the values from December to March were significantly lower than those of the normal levels （P<0.05）. It illustrated that Phyllostachys edulis was stressed and photochemical efficiency（ФPSⅡ） was decreased in that three months. Fv/Fo was the same as Fv/Fm. Photochemical quenching coefficient （qP） gradually decreased from October to March then rose. On the contrary， nonphotochemical quenching coefficient （qN） gradually rose then decreased. The study showed that low temperature stress reduced the proportion of light energy which used for photochemical electron transport， and decreased the photosynthetic carbon assimilation of Phyllostachys edulis.

Key words: Phyllostachys edulis forest, ecosystem, net ecosystem carbon exchange, chlorophyll fluorescence